I was driving in Manhatten last weekend when I saw a crane about 65 or 70 stories high working on a building, which got me wondering a few things. First, where does the crane “park” when not in use? The thing must be visabe for several miles. Secondly, how did it get there in the first place? Manhatten is full of people and taxis and stuff, while the crane is huge, it suprises me that the thing even fits in Manhatten. I asked a friend of mine who told me they probably drove it there, but I’m having trouble believing it. I mean, I don’t ever recall driving down seventh ave with a black lexus behind me and a seventy story crane drivng ahead of me. So, what’s the straight dope?
I don’t think they drive the entire thing there all at once, but rather bits of it at a time. Then they assemble it on-site and continue to add height to it as the building is built.
At least that’s what this Howstuffworks.com article says.
Tha was way far above anthing that I could comprehend. I’m thinking that it would take forty men to lift one of those bars. I’m having trouble imagining how long it would take to make one five stories, neverminf seventy.
It ‘bootstraps’ itself, if you will. The crane is designed so that by adding sections to itself, it can grow upwards. It’s sort of like how they used to lay railroad lines, where they’d have a train drive out to the end of the line hauling more rails and ties, crews would then hop off the train, lay the rails and ties, the train would then move forward until it got to the end, wherein crews would lay more ties, only instead of being horizontal, it’s vertical, and instead of needing crews of gang workers, the crane does it all by itself.
What you saw 70 stories up was a ‘pillar’ crane.
A mobile crane starts the basic assembly at or near ground level and maintians a supply of pillar sections for the pillar crane use to bootstrap itself up one floor at a time.
History channel may have an ephisode showing it sometime. Best seen to understand the operation, hard to describe in words.